Claude's 1M Context Window Is GA at Standard Pricing

My notes

Summary

Anthropic has made the full 1M token context window generally available for Claude Opus 4.6 and Sonnet 4.6 at standard pricing - no long-context premium. The key practical impact: Claude Code Max/Team/Enterprise users on Opus 4.6 now get 1M context automatically, meaning far fewer forced compactions and more intact sessions. Opus 4.6 scores 78.3% on MRCR v2 (multi-round context retrieval), the highest reported among frontier models at that context length.

Key Insight

• No pricing penalty: $5/$25 per million tokens for Opus 4.6, $3/$15 for Sonnet 4.6 - same rate at 900K tokens as at 9K. Previously long-context incurred a multiplier.
• Media limits expanded: 600 images or PDF pages per request (up from lower limits).
• 78.3% MRCR v2 score: This is the retrieval-in-context benchmark at 1M length. Useful calibration point - the model can find relevant details but is not perfect.
• Fresh context > long context: The most practised HN users strongly recommend starting new sessions rather than riding compactions deep into context. CLAUDE.md instructions dilute through compactions by default unless a hook re-inserts them.
• Subagents are the real unlock: Each subagent starts with a clean context; the orchestrator only sees results, keeping its own context low. This lets you churn through millions of output tokens across a session without degradation - documented at code.claude.com/docs/en/agent-teams.
• Practical cap in use: Experienced users rarely need 1M raw. Workflows using code maps (Flash for indexing) + auto-context (targeted file selection) keep individual requests to 30K–80K even on large repos. 1M is a ceiling, not a target.
• Context poisoning is real: Bad conversation history degrades performance. Rollback (Escape twice or /rewind) rather than steering is the correct recovery pattern.
• AI-generated slop risk: Non-technical users building apps with Opus alone produce working but insecure code. Production readiness is not the same as task completion.